Cyclic acetals of 2,4-hexadienal

ABSTRACT

THERE ARE PROVIDED NOVEL ODORANT COMPOSITIONS DERIVED FROM THE CONDENSATION OF 2,4-HEXADIENAL WITH CERTAIN DIOLS. THESE NOVELS ACETALS HAVE A GENERALLY FRUITY CITRUS TYPE ODOR.

United States Patent 3,769,303 CYCLIC ACETALS 0F 2,4-HEXADIEN AL William M. Easter, Jr., Hasbrouck Heights, and Robert F. Tavares, Cedar Grove, N.J., assignors to Givaudan Corporation, Clifton, N .J. No Drawing. Filed July 7, 1971, Ser. No. 160,554 Int. Cl. C07d 17/00 US. Cl. 260338 1 Claim ABSTRACT OF THE DISCLOSURE There are provided novel odorant compositions derived from the condensation of 2,4-hexadienal with certain diols. These novel acetals have a generally fruity citrus type odor.

FIELD OF THE INVENTION Odorant acetals.

DESCRIPTION OF THE PRIOR ART -It is known in the art to condense aldehydes or ketones with diols to produce the corresponding cyclic acetal or ketal. However, it has not been known heretofore, that the condensation of 2,4-hexadienal with dihydroxy alkanes or dihydroxy alkenes would give rise to a system having desirable odorant qualities.

SUMMARY OF THE INVENTION The compounds of the present invention have the In accordance with the process of the present invention 2,4-hexadienal is reacted with the appropriate diol in the presence of an acid. The reaction may be illustrated as follows:

HO-CHz 150- Ha I i1 HO-CH7 =0 0 HO-C II The compounds of the present invention are useful odorants having a fruity or fluoral citrus type of odor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the process of the present invention 2,4-hexadienal is taken up in an appropriate solvent, suitably reaction inert solvent capable of forming an azeotrope with water, and is heated with the appropriate diol in the presence of an acid catalyst.

Since the removal of water formed during the reaction is beneficial to drive the reaction to completion, common hydrocarbon azeotroping solvents such as cyclohexane, benzene, toluene, xylene, and the like are preferred. These listed solvents are purely illustrative and are not critical to the invention since the reaction can be run in any reaction inert solvent or in the absence of solvent.

The catalyst ecessary to provide an acidic medium may be an organic or inorganic acid. Thus, there may be used citric acid, tartaric acid, phosphoric acid, p-toluene sulfonic acid and the like. These listed catalysts are purely illustrative and not critical to the invention.

The relative amounts of reactants and catalyst in the reaction are not critical. We have found a small excess of the diol, suitably from about 10 to 50 mole percent relative to the hexadienal, and an amount of catalyst of about V2 to 1% by weight based on hexadienol to be appropriate. Such amounts of reactants and catalyst are merely illustrative and are not critical to the invention.

In the preferred procedure the mixture is heated under reflux with vigorous agitation until no further water is produced by the reaction mixture. It is particularly appropriate to carry out the reaction with a Dean-Stark trap. The reaction mixture is cooled, Washed to neutrality with water and a mild base such as, suitably, saturated aqueous sodium bicarbonate or the like, the solvent removed by distillation, and the residue distilled under reduced pressure. The above process is provided as an illustration of the preferred procedure but is in no way to be considered as critical to the invention. Any reaction conditions known in the art to produce cyclic acetals from aldehydes and diols would be applicable to this invention.

In accordance with the process of the present invention closely related compounds were prepared utilizing other dihydroxy alkanes as reagents with 2,4-hexadienal. In these related compounds listed in Table I R R R R and R are alkyl groups or hydrogen atoms.

TABLE I o o I l x" R: Br R1 R2 R1 R2 R2 Ra R4 R2 Rs R4 R5 R1 R: R1 R1 Dlhydroxy alkane 1,2-dihydroxyethane. 1,2-dihydroxypropane. 2,3-dihydroxybutane. H H H H 1,3-dihydroxypropane. CH H H H 1,3-dihydr0xybutane. CH3 H H H 2,4-dihydroxypentane. CH H H CH3 2,4-dihydroxy-2methylpentane.

/CH CH; CH; H 1,3-dihydroxy-2,2,4-trimethylpentane. s

9 H CH; CH: OH: H z. 1,3-dihydroxy-2,2-dimethylbutane. 10 H H CH3 CH3 H 1,3-dihydroxy-2,Z-dimethylpropane. ll..- 1,4-but-an diol-2-buten 1, l-diol. 12- H H It is the interesting and surprising finding of this inven- B.P. C./9 mm 107 tion that of all the compounds prepared only two possess n 1.5150 any utility as odorants namely, 2-(1,3 pentadien-1-y1)- Carbonyl percent by IR 0.0 1,3-dioxolane (No. 1 in Table I) and 2-(1,3-pentad1en-1- V. pc. percent 98.7 y1-l,7 dihydro-1,3-dioxepin (No. 12 in Table I). The re- Colorless. maining compounds either have no odorant etfect or have EXAMPLE II no adverse effect upon odorant compositions to which they are added.

2-(1,3-pentadien-l-yl)-1,3-dioxo1ane, prepared by condensing ethylene glycol with 2,4-hexadienal has a sweet, green, jasmine like odor, having a top-note of orange peel which makes it particularly useful in perfume compositions such as citrus, bergamot, and floral odors. 2-(l,3- pentadien-1-yl)-4,7-dihydro 1,3 dioxepin has a fruity citrus note coupled with a green bergamot pineapple odor, having a sour lime touch. It is useful in perfume compositions of the bergamot, lime and general citrus type.

These compounds may be used in ratios of from about 10 to about 200 parts per thousand of odorant base compositions containing them.

The compounds may be used to prepare odorant compositions which may be used as odorant bases for the preparation of perfumes and toilet waters by adding the usual alcoholic and aqueous diluents thereto, approxi mately 15-20% of base would be used for the former and approximately 3-5 would be used for the latter.

Similarly, the base compositions may be used to odorize soaps, detergents, cosmetics, or the like. In these instances a base concentration of from about 0.5 to about 2% may be used. All the above concentration ratios are by weight.

EXAMPLE I Preparation of 2-(1,3-pentadien-1-yl)-4,7-dihydro- 1,3-dioxepin Into a one liter flask equipped with heating jacket, agitator and a condenser fitted with a Dean-Stark trap was charged 96 gms. 2,4-hexadienal, 97 gms. of Z-butene- 1,4-diol, 1 gm. of citric acid and 160 gms. cyclohexane. With vigorous agitation the mixture was refluxed until the collection of water in the Dean-Stark trap was completed. The reaction mixture was cooled and washed neutral. The solvent was removed and the oil vacuum distilled. There was recovered 147 gms. of 2-(1,3-pentadien-1-yl)-4,7-dihydro-1,3-dioxepin having the following physical properties:

Preparation of 2-(1,3-pentadien-1-yl)-1,3-dioxolane B.P C./8.5 mm-.. 82 11 1.4975 Carbonyl percent by IR 0.0 Colorless.

EXAMPLE HI The following citrus type odorant base formulation was used to demonstrate the use of 2-(1,3-pentadien-1-yl)-4,7- dihydro-1,3-dioxepin. All of the parts in the example are by weight.

Linalool synthetic 8 Citral synthetic 12 Geranyl acetate extra 20 Linalool acetate 300 Orange oil, C.-P. Petigran, S.A. 20 Triethyl citrate Terpinyl acetate extra Lemon terpenes 2-(1,3-pentadien-1-yl)-4,7-dihydro-1,3-dioxepin 100 The dioxepin imparted a neutral citrus quality and contributed to the bouquet of the perfume base. Without the dioxepin the base seemed unfinished and of inferior quality.

5 EXAMPLE IV If the formula of Example HI is modified by replacing the 2-(1,3-pentadien-l-yl)-4,7-dihydro-1,3-dioxepin with 2-(1,3-pentadien-1-yl)-1,3-dioxo1ane, the dioxolane imparts a natural citrus quality which is a definite improvement over the perfume without the dioxolane.

EXAMPLE V If the formulae of Example HI is modified by replacing the 2 (1,3-pentadien-1-yl)-4,7-dihydro-1,3-dioxepin 10 6 We claim: 1. 2-( 1,3-pentadien-1-yl) -4,7-dihydro-1,3-dioxepin.

References Cited UNITED STATES PATENTS 3,268,559 8/1966 Pawloski et a1. 260338 3,381,039 4/1968 Marbet 260338 X ALEX MAZEL, Primary Examiner J. H. TURNIPSEED, Assistant Examiner US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No Dated October 50, 1975 Inventor(s) William M. Easter, Jr.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

1. Column 2,- line 32: "necessary, "n" omitted; line 41, hexadiengl, should be hexadienal.

2. able (columns 3 and 4) 7 correct line 11 and 12 of table line ll; should read 1, 4-butandiol, line 12; should read Z-buten-l, 4-diol.

3-. Column 3; line 33 and 34-; the compound name is 2- (l, 3-pentadien-lyl)-4, 7-dihydro-l, 3 -d'ioxep1n 4. Column 4; VPC rather than V.pc. on line 33.

Zignec? sealed chi s 8th day of Apri l 1975.

"'7' J 1 and -rasemarAs F ORM PO-105O (10-69) USCOMM-DC 60376-P69 0.5. GOVERNMENT PIINIING OFFICE: 

